Conventionally, there has been known a valve device with two valve bodies for selectively opening and closing a passage between a fuel tank and a canister in a vapored fuel processing device (e.g., refer to Patent Document 1: JP 2015-25488 A).
Such a valve device typically decreases an opening degree of the passage to prohibit a large amount of vapored fuel from flowing into the canister at once when a pressure in the fuel tank is relatively high, whereas the valve device typically increases the opening degree of the passage so that, to immediately decrease the pressure in the fuel tank, a large amount of the vapored fuel can flow toward the canister when the pressure in the fuel tank is relatively low.
In a configuration of Patent Document 1, the valve device includes a passage defining member, a main valve body, and a sub valve body, as described below.
A passage is defined in the passage defining member and fluid flows through the passage. The main valve body is housed in the passage and is operated by an electromagnetic solenoid to selectively open and close the passage.
The sub valve body is disposed in the passage downstream of the main valve body. The sub valve body is operated by a pressure difference, which is generated when the passage is opened, between a pressure at an upstream side of the sub valve body and a pressure at a downstream side of the sub valve body. The sub valve body decreases an opening degree of the passage as the pressure difference increases.
A valve seat is annually formed in the passage defining member and the main body seats on the valve seat. The valve seat has an inner circumferential surface forming a portion of the passage, and the passage is closed when the main valve body seats on the valve seat.
According to the valve device of Patent Document 1, a downstream side of the valve seat in the passage and the fuel tank are not in communication with each other when the main valve body seats on the valve seat and closes the passage.
Hence, since the sub valve body does not always expose to vapored fuel, it is possible to suppress occurrence of malfunction of the sub valve body due to adhesion of adhesive material to the sub valve body.
In the valve device of Patent Document 1, a portion of the passage defining member, more specifically, a cylindrical end portion close to the canister, is separately provided with a main body of the passage defining member in advance in order to set the sub valve body together with a return spring inside the passage. Then, the sub valve body and the return spring are housed inside the main body of the passage defining member, and thereafter the cylindrical end portion of the passage defining member is fit into the main body and is connected to the main body by welding. As a result, the sub valve body and the return spring are held with the main body and the cylindrical end portion to be set within the passage. Therefore, a connection portion is formed in the passage defining member, and thus strength of the passage defining member at the connection portion may be decreased.